Scientific Aims: Toward better understanding of the pathogenesis and treatment of all types of cerebrovascular disease including acute cerebral infarction, chronic cerebral ischemia with dementia and intracranial hemorrhage with subarachnoid bleeding. The research design includes clinical investigations and therapeutic trials in patients with stroke as well as experimental investigations of basic models in animals. Changes in cerebral blood flow and energy metabolism resulting from acute cerebral ischemia will be measured. Any accumulation or depletion of neurotransmitters (serotonin, norepinephrine, dopamine) in ischemic brain will be correlated with blood flow and energy metabolism. The effects on these measurements of drugs designed to block, deplete or influence such neurotransmitters (propranolol, phenoxybenzamine, reserpine, etc.) will be measured. Complicating factors in subarachnoid hemorrhage (spasm, edema, communicating hydrocephalus, intracerebral hematoma) will be defined using new regional cerebral blood flow techniques. Neuropsychological testing will be utilized to quantitatively define deficits in the stroke syndromes as well as the outcome of new forms of therapy. Thrombolytic disorders as risk factors in stroke and subarachnoid hemorrhage will be investigated. The role of disturbance of lipid and betalipoprotein metabolism in human cerebral atherogenesis will be correlated with early histochemical changes of cerebral atherosclerosis obtained at autopsy.